Method of producing lined pipe bends



Feb. 10, 1948-. s. i= oBAus METHOD OF PRODUCING LINED PIPE BENDS FiledJune 15, 1945 INVENTOR. 522272463 fiobaz fi,

Patented Feb. 10, 1948 UNITED innrnonnnrnonucmfinutn ,l lcsnuunseofilllinois I i henna-non ,runeqie, 1945, senn uo;;saaisv Thisinvention relates to pipe bends-and hasto do'with the production 'oflined pipe-tberrds;

-In carrying out chemicalgprocessegand irrthe treatment ofcertainfoodpro'ducts;'such' astmilk, it is of importance. that the pipesorcorrdilits through which the materials beingprocesse'dpass beresistant to such materials. ":Tothat end; it; is known-to provide "pipegofflia metal which would be attacked by .the materials 'beingprocessed, these pipes having .thereiniliners .of metal'idissimilarto"that .of 'the pipe'ian'd which wfll-notbe attacked by the materialsbeing, processed. "It'is of importance thatthe "liner'fitsnuglythe'interior tively thereby. in" aiineof pipingth'ere'usually isjpresenta c'onsiderable 'number 'of "elbows or bends. :It' is ofpa'rticu'lar"importance, in a" line of piping used for handlingv materialsoftheLcharacter referred 'to,jthat""the liningyof 'the'felbows or bendsfit tightly the interior thereof, since there is risk, at thejunctures"between the ben'd and the ends of the. straight run" crpipe," that" acertain amount ofthe material may enter be-' tween the parts. .Ifthelining of the elbow is not fitted to the interior thereof so as toprovide a substantially fluid-tight' seal therewith,-the material mayenter between the elbowand its-lining and attack the-outer wall :of theelbow.

It is quite difficult to insert into a pipe bend, such as an elbow, alining-and to attained-accurate fit between the lining'and the eilbowthroughout "the full extent thereof, particularly at theendspf-the-elbow whilealso assuring' 'that the lining will fit withinthe elbow so tightly as to provide a substantially fluid-tight sealtherebetween. My invention is directed to the method whereby a pipebend, such as an elbow, may be produced with the lining fitting withinthe elbow accurately throughout its full extent and in tight sealingcontact therewith. More specifically, I provide a cylindrical pipestraight lengthwise with a suitable liner fitting therein, and expandthe liner and the pipe radially by interior pressure applied thereto andalso bend them lengthwise as a unit about the center of the curvature ofthe desired elbow, thereby assuring accurate and tight fit of the linerwithin the elbow so that the outer Wall of the elbow efiectively backsthe interior liner and the latter has sealing contact with the innersurface of the outer wall of the elbow.

In the drawings:

Figure 1 is a fragmentary lengthwise sectional View of a length of pipeand a liner therein, show- (cuesnew) V *ing"the relative wallthicknesses of the llnenand the-pipe;

Figure 2 is a lengthwise *sectional viewthrough a portion-of the pipeand the liner of- -Figure lbeing-moved cveracurved'interior-expanding'man- -drel," show-n;-in'blejzationflillustrating the-manner in whichtheliner and the *pipe 1 are expanded radially "and are bent lengthwiseinto fdejsired curvature, this: *view" being on -a reduced -sca lerelative 'to Figure 1 '7, and the liner being shown gas-of increasedwall thicknessmelative to thewall 'thickess of the-pipeforclearnessbfiillustration; and

Figure 3 is-a central :lengthwise seetional view of 1a lined; elbowproducedffinaccordance with my invention, on an'eii'largedscaleand-taken in the plane of, the euryethereof.

The 'first 'step 'irrthe method of my invention consists 'in providin'g;a liner 4, of proper size-etc fit snugly -within;:;a straightcylindrical pipe fi, which istoprovide theputer wallet-the elbow. 'Theliner 4 is of a 'difierent metal than: or ame'tal dissimilarto,'thj'mtalj o'fthe pipe 5. For ex-i ample, liner {4- ma be orstainless-steel; "copper, or other suitableymetalgor jaiiioy-resistanttofthe materials *to bejprqcessed and the --pipe-'5-mjay be formed ofwrought iron, "ordinary "steel; -01 other isuitable' "metal capable tofresisting the stresses to which it "may be subjected. Ordinarily, ,thewall" thickness ;of the liner ,4" should be about one th-irdjfjthe--wall thickness offthe "pipe 5;: asshown in Figure 1; ,but'it willgbeunderstood thati-the ratior'ofthe wall thicknessof the *liner to thatof" the pipe'maywary considerably. depending upon conditions. Likewise,the wall thickness of the pipe may vary considerably, depending upon thediameter of the elbow to be produced and other factors.

After the liner 4 has been properly inserted into the pipe 5, the latterand the liner, as a unit, are expanded radially to the desired diameter,and are bent lengthwise to the desired curvature, by relative endwisemovement between liner 4 and pipe 5 as a unit and an interior curvedexpanding mandrel 6. This mandrel 6 comprises an inner straightcylindrical portion 1 of uniform diameter, an intermediate portion 8merging at its inner end into the outer end of portion 1. and ofincreasing diameter outward, and an outer portion 9 of uniform diameterthe same as the interior diameter of the desired bend, this outerportion 9 merging at its inner end into the outer end of intermediateportion 8 and being curved about a center corresponding to the center ofcurvature of the desired bend. H desired,

instead of the mandrel 6, any other suitable mandrel may be used; forexample, the mandrel disclosed in the patent to James Hall Taylor, No.2,181,384.

The liner 4 is of an interior diameter to fit snugly over .inner'portionl of ;the mandrel 6. and the pipe 5 and the liner 4 are expandedradially and bent lengthwise to desired curvature by relative lengthwisemovement between pipe 5 and liner 4, as a unit, and mandrel 6; That maybe accomplished by moving the pipe 5 and sonable limits.

function being that of a protective imi'r coating or lining. Theultimate thickness of the lining of the elbow depends upon the wallthickness of the original liner, and by using liners of different wallthicknesses the lining of the elbow produced may be of any desired .wallthickness, within rea- If the elbow or bend is to be welded in a line ofpipe, the end portions of the outer wall 5a thereof are removed for asuitable distance, as at 5b, so that the ends 4b of ',.liner 411 projecta short distance outward beyond liner 4 lengthwise toward the mandrelwhile the latter remains stationary, by moving the mandrel lengthwisethrough the pipe 5 and liner-4' as a unit While they are heldstationary, or by imparting lengthwise movement in opposite directionsto the mandrel and to the pipe'li and liner 4. It will be assumed, forpurpose of description, that the mandrel 6 remains stationary while thepipe 5 and liner 4 are movedas a unit thereover.

The end portion of the pipe and liner unit, comprising the pipe 5 andliner 4, is first positioned about straight portion 1 of mandrel 6, andis heated in a known manner and by suitable known means to properworking temperature. The pipe and liner unit is then fed lengthwise overthe mandrel and, in the area thereof, is

maintained at properiworking temperature. As the pipe and liner unitadvances along the man drel, it is expanded radially thereby and, as itexpansion is produced by pressure applied to the inner surface of theliner, the liner is forced tightly into contact with the inner surfaceof the pipe so as to fit accurately therein and provide a substantiallyfluid-tight seal therewith.

After the pipe and liner unit has been expanded and formed to thedesired curvature, as above, it is cut to proper length to produce thedesired bend, such as the elbow of Figure 3, from which it will be notedthat the wall thickness of the liner 4a is approximately one-fifth thewall thickness of the outer wall in of the elbow, originally the wall ofthe pipe. In general, the liner 4a of the elbow may be quite thinrelative to the outer wall at thereof, its main the ends of wall 5a. Thebend thus formed is intended for use with lined pipe having the endportions of the outer walls thereof removed in a similar manner, as willbe understood. When the bend is properly assembled with the pipe ends,for welding, each end of the bend defines with the adjacent pipe end awelding trough closed at its bottom by the endwise abutting projectingend portions of the liners, which facilitates the welding operation andguards against objectionable entry of molten metal into the pipe withresultant formation therein of icicles.

I claim:

1. The method of producing lined pipe bends, which comprises insertinginto a metal pipe a liner of dissimilar metal, simultaneously andprogressively expanding said pipe and liner radially by internalpressure whereby said liner is forced into intimate contact with theinner surface of the expanded pipe, and forming said pipe and liner as aunit about a center corresponding to the center of curvature of thedesired bend simultaneously with said radial expansion thereof.

-2. The method of producing lined pipe bends, which comprises insertinginto a metal pipe a liner of dissimilar metal, and expanding said pipeand liner radially while simultaneously forming them lengthwise to thecurvature of the desired bend, by relative lengthwise movement betweensaid pipe and liner as a unit and an interior curved mandrel;

' STANLEY ROBAUS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

